1. Field of the Invention
The present invention relates to a solid-state image pickup apparatus with high-speed photometry and a signal reading method therefor, more particularly to a solid-state image pickup apparatus, which includes an array of photosensitive cells integrated in higher density and arranged obliquely adjacent to each other, that is, in the so-called honeycomb structure having the lines or rows of cells offset from each other by a length equal to the half of the pitch of the cells in line or row, to accomplish an increased resolution, and which is advantageously applicable to an electronic still camera, an image input apparatus and the like.
2. Description of the Background Art
With reference to a solid-state image pickup apparatus taking the so-called honeycomb arrangement, various kinds of proposals have been disclosed in Japanese patent publication No. 31231/1992, Japanese patent aid-open publication Nos. 77450/1994 and 136391/1998. In Japanese patent publication No. 31231/1992, first electrodes meander along photosensitive cells which are arranged in the offset manner, so as to form a wavy shape pattern, and second electrodes are formed in another wavy pattern opposite in phase to the former. Other photosensitive cells are arranged in a region where the first and second electrodes separate so as to enable a signal to be read out from each cell via means for selectively coupling with the second electrodes, in response to an enable signal supplied to the first electrode, thus further increasing the resolution and the sensitivity of the solid-state image pickup apparatus from conventional. In the publication, the photosensitive cells are exemplified as being formed in an octagonal pattern.
In Japanese patent laid-open publication No. 77450/1994, the shape of photosensitive cells is formed as a square which is one of diamond shapes, and each side thereof forms an angle of 45 degrees in a vertical direction, so that its aperture ratio is made to be high, thus miniaturizing the solid-state image pickup apparatus. Particularly, by adopting a honeycomb arrangement, an increase in a vertical resolution is achieved. Moreover, a micro-lens is disposed on each photosensitive cell, thus increasing a light receiving efficiency.
In Japanese patent laid-open publication No. 136391/1998, meandering charge transfer devices of two lines are arranged between photoelectric conversion devices in a column direction, which are disposed so as to be adjacent to each other in the same row and relatively shifted by approximately the half of the interval between themselves in the adjacent rows, and the charge transfer devices are used for transferring the charge from the photoelectric conversion devices obliquely adjacent to each other. A spurious signal aliasing such as moiré is suppressed while achieving a high-density integration of the photoelectric conversion devices and an increase in a photoelectric conversion efficiency.
In the foregoing Japanese patent publication No. 31231/1992 and Japanese patent laid-open publication No. 77450/1994, attention is paid only to the structure of the device in aiming at a high-density integration. Moreover, in Japanese patent laid-open publication No. 136391/1998, descriptions for the structure and the shape of the device and the positional relation of the color filters are made. Then, descriptions of whole-pixel reading out using these relations are made.
By the way, it is understood that a high-density integration time for a reading out of signal charge obtained by a photoelectric conversion. For example, in a mode of controlling a light measurement or a photometry in which an automatic focus adjustment (AF) and an automatic exposure (AE) control are performed, there are demands for shortening a time required for reading out the signal charge and for finishing a preparation for an image pickup without delay. For photosensitive cells, the high-density integration of the image pickup devices and shortening of the time of the signal reading out are antinomic demand, which are contradictory to each other.
Particularly, when the signal is read out from the photosensitive cells adopting a honeycomb arrangement in the mode of controlling a light measurement, a breakthrough by a different method from conventional methods is needed.